1. Field of the Invention
The present invention relates to a coating head and a coating apparatus and, more particularly, to a coating head and a coating apparatus suitable for forming a coating film such as a magnetic recording layer on a flexible supporting member traveling while being supported by travel guide devices such as guide rollers.
2. Description of the Related Art
Conventional methods for forming a coating film on a flexible supporting member traveling continuously while being supported by travel guide devices such as guide rollers include application-type methods such as roller coating, dip coating and fountain coating, and measuring-type methods such as air-knife coating, blade coating and bar coating. As methods using a combination of an application-type method and a measuring-type method in one place, extrusion coating, slide bead coating, curtain coating and so on have been used.
Extrusion coating among such methods is suitable for forming a thin film, a multilayer film or the like and has been introduced for manufacture of magnetic recording mediums, particularly magnetic tapes because the productivity (coating speed) when extrusion coating is used is high. The applicant of the present invention has made various improvements and propositions relating to this kind of coating in documents including those shown below and has achieved certain effects.
Japanese Examined Application Publication No. 5-8065 relates to a method of extrusion coating of one layer and an improvement in the shape of a coating head, Japanese Examined Application Publication No. 6-77712 relates to a method of extrusion coating of a plurality of layers and an improvement in the shape of a coating head, particularly a specified end radius of curvature, Patent Publication No. 2942938 relates to a method of extrusion coating of a plurality of layers in which two-layer coating is performed with a coating head after precoating, and Japanese Patent Application Publication No. 2000-343019 relates to an extrusion application method in which the surface roughness of a coating head is improved to improve a coating condition.